Burrito, that's obviously the trail leading to the Gorge Amphitheater, and that is obviously a dude freaking the fuck out on acid. In the part of the video you can't see, he executes that excellent dive you see him attempting out in that field a couple times -- arms at his side, nose in the air, totally like an antelope. Hence the name Antelope Man. He is a hero to us all.
I think for a brief moment, Sigur Ros defied the existence of existence and created our own parallel dimension where all dimensions became meaningless and we were joined together in a massive spiritual oneness of Icelandic mojo.